Two-planar deflector for dispersing and depositing nonwoven filamentary structures

ABSTRACT

AN APPARATUS FOR AUGMENTING DISPERSAL AND FOR IMPROVING DEPOSITION OF A PLURALITY OF CONTINUOUS FILAMENTS ONTO A CONTINUOUSLY MOVING SURFACE WHEREBY RANDOM DISTRIBUTION OF THE FILAMENTS IS PROVIDED FOR THE PRODUCTION OF UNIFORMLY DISTRIBUTED NONWOVEN WEBS. A NONMOVING TWOPLANAR DEFLECTOR IS POSITIONED NEAR THE EXIT OF AN ASPIRATOR SO AS TO PROVIDE GREATER OPENNES AND GREATER RANDOM LAYDOWN OF FILAMENTS.

May 29, 1973 w. P. LIPSCOMB ET AL 3,736,211 TWO-PLANAR DEFLECTOR FORDISPERSING AND DEPOSITING NONWOVEN FILAMENTARY STRUCTURES Filed Sept.28, 1971 2 Sheets-Shem 1 3 V I Q h n.) 7

INVENTOR. Walter P. Lipscomb BY 6 rlund L. Tumor ATTO EY May 29, 1973 w.P. LIPSCOMB ETAL 3,736,211

TWO-PLANAR DEFLECTOR FOR DISPERSING AND DEPOSITING NONWOVENFILAMEN'I'ARY STRUCTURES Filed Sept. 28, L971 2 Sheets-Sheet 2 I l5 ,6 lI ll /9 INVENTORS Waller I? Lipscomb /8 Garland L. Turner United StatesPatent O 3,736,211 TWO-PLANAR DEFLECTOR FOR DISPERSING AND DEPOSITINGNONWOVEN FILAMENTARY STRUCTURES Walter Peter Lipscomb and GarlandLinwood Turner, Chesterfield County, Va., assignors to Allied ChemicalCorporation, New York, NY.

Filed Sept. 28, 1971, Ser. No. 184,420 Int. Cl. D04h 3/00 US. Cl. 1564417 Claims ABSTRACT OF THE DISCLOSURE An apparatus for augmentingdispersal and for improving deposition of a plurality of continuousfilaments onto a continuously moving surface whereby random distributionof the filaments is provided for the production of uniformly distributednonwoven webs. A nonmoving twoplanar deflector is positioned near theexit of an aspirator so as to provide greater openness and greaterrandom laydown of filaments.

CROSS-REFERENCE TO RELATED APPLICATIONS The invention herein set forthis related to the inventions described in copending applications Ser.No. 184,- 422 entitled Foraminal Apparatus for Splaying and DepositingNonwoven Filamentary Structures, filed on Sept. 28, 1971 in the name ofWalter P. Lipscomb and Garland L. Turner, and Ser. No. 184,421 entitledApparatus for Splaying and Depositing Nonwoven Filamentary Structures,filed on Sept. 28, 1971 in the name of Walter P. Lipscomb and Eli B.Shelburne, Sr., wherein different apparatus for improving the dispersaland deposition of a plurality of continuous filaments onto acontinuously moving surface are disclosed.

BACKGROUND OF THE INVENTION This invention relates to an improvedapparatus for dispersing and depositing filaments. In particular, itrelates to an apparatus for augmenting the dispersal of continuousfilaments onto a receiving surface so as to form a nonwoven web ofrandomly disposed filaments.

Nonwoven webs formed from continuous filamentary materials which havebeen laid on a receiving surface in a random configuration are wellknown in the art. In the formation of such webs, great care isfrequently taken to ensure that the filaments are maintained apart fromeach other and that interfilamentary entanglement and the formation offilament aggregates are avoided.

Nonwoven webs comprising multi-filaments are commonly formed byforwarding the filaments from a source of supply, such as a meltspinnerette, to and through an aspirator and then depositing thefilaments at high velocity onto a moving surface. In the production ofnonwoven products having a substantial width, there must be providedeither a plurality of aspirators for depositing a plurality offilamentary bundles in a random manner upon the moving surface or theremust be provided a means, normally unduly complicated and cumbersome, tomove the aspirator over the width of the product to be produced.

When depositing filaments from a conventional aspirator onto acollecting surface, the filaments will spread out within the confines ofthe aspirator boundary. However, the filament distribution in the jetstream is not always uniform and random and is often restricted to asmall laydown area; for example, a web width not exceeding eight incheswhen a fixed aspirator jet is situated at a distance of one to threefeet from the receiving surface.

Some of these deficiences have been overcome by impinging the filamentsagainst a, single deflecting plane 3,736,211 Patented May 29, 1973 ICCSUMMARY OF THE INVENTION Accordingly, it is an object of this inventionto provide an apparatus for augmenting dispersal of filaments which aredeposited onto a receiving surface so as to form a web. It is a furtherobject of this invention to provide a simple, reliable, inexpensive, andeasily constructed apparatus for more expeditiously spreading filamentsand thereby for producing superior nonwoven webs having high integrity.A further object of this invention is the provision of a filamentdispersing and depositing means employing no moving parts that tend togenerate repeating patterns of filament laydown which are detrimental toweb strength. Further objects and advantages of the present inventionwill become apparent by reference to the following specification anddrawings.

In attaining the foregoing objects, this invention features an apparatusfor augmenting dispersal and for improving deposition of filaments ontoa moving receiving surface in a randomly dispersed manner to form anonwoven web. Such apparatus comprises, in combination, an aspirator toforward the filaments at a high velocity and a two-planar deflector tosplay the filaments widely and randomly as such filaments pass from theaspirator to the moving receiving surface. The two-planar deflectorconsists of a first plane being rigidly aflixed in one spatial positionnear or close to the aspirating means exit and a second plane beingrigidly aflixed in another, adjacent spatial position. The two-planardeflector is positioned near the exit of the aspirating means such thata majority of the filaments exiting from the aspirator impinge on thetwo-planar deflector. The first plane or its straightline extensionintersects the second plane, forming an angle greater than 90 degreesbetween the impinging surfaces of the two planes. The first plane makesan acute angle a of between 0 and 60 degrees with a line parallel to thecenter line of the aspirator exit passageway, the angle being measuredin the general direction of forward motion of the moving receivingsurface. The second plane makes an acute angle s of between 20 anddegrees with a straight-line extension of said first plane. The sum of aand [3 is always less than degrees.

In a preferred embodiment of this invention, the twoplanar deflector hasan angle at of between 25 and 50 degrees and an angle 3 of between 35and 60 degrees, the sum of a and 5 being between 45 degrees and 87degrees.

Also preferably, the two-planar deflector is affixed near the aspiratorexit in a manner such that there is a distance of approximately from 3to 26 times, more preferably from 4 to 15 times, the diameter of theaspirator exit passageway between the aspirator exit and the area ofinitial substantial contact of the filaments on the two- .planardeflector. More preferably, each plane of the twoplanar deflector issubstantially rectangular in shape. The first plane of suchrectangular-planed deflector has a length measured in a directionproceeding from the aspirator exit passageway of approximately from 3.5to 2'0 times, even more preferably from 4 to 10 times, the diameter ofthe aspirator exit passageway and a width approximately from 5 to 15times, even more preferably 7 to 13 times, the diameter of such exitpassageway. Also, the second plane of such rectangular-planed deflectorhas a corresponding length of approximately from 1.5 to 25 times,

even more preferably from 2 to 4 times, the diameter of the aspiratorexit passageway and a corresponding widthof approximately at least 5times, even more preferably 7 to 20 times, the diameter of such exitpassageway. Alternately, the second plane of the two-planar deflectormay be a quadrilateral having the length and width ranges similar tothose described above for the rectangularplaned deflector and alsohaving substantially equal lengths; however, such quadrilateral secondplane has widths such that the width farthest from the aspirator exit issubstantially wider than the other parallel second plane width.

A feature of this invention is its quick and easy adaptability for usewith many conventional aspirator jets in dispersing and depositingfilamentary materials onto a moving receiving surface.

The method utilizing the apparatus for this invention comprises, ingeneral, the utilization of the two-planar deflector in combination withan aspirator whereby filaments, preferably forwarded from a spinneretteof a spinning mechanism and thereafter from a drawing mechanism, areforwarded through a high velocity fluid jet of an aspirator. Subsequentthereto, the aspirator jet stream propels the filaments onto thetwo-planar deflector whereby the filaments are deflected onto acontinuously moving, preferably foraminous, surface in the form of auniform nonwoven web comprising randomly disposed, substantiallyuniformly distributed filaments. Deposition of the filaments may beaided by a suction chamber located underneath the moving surface.

The described apparatus can be readily used for dispersion of filamentsor, alternately, strands, yarns, slivers or other similar forms ofmaterials, or mixtures thereof. Such materials include any fiber-formingthermoplastic polymer from which filaments can be obtained. Thesematerials include: polyamides, for example, poly(epsiloncaprolactam)(hereinafter nylon 6) and poly(hexamethylene adipamide) (hereinafternylon 66); linear polyesters, for example, po1y(ethylene terephthalate);acrylonitrile polymers and copolymers; olefinic polymers, for example,polyethylene, polypropylene, and polyvinyl chloride; and celluloseacetates. Preferred materials include nylon 6, nylon 66 and poly(ethylene terephthalate).

This invention will be more clearly understood and additional objectsand advantages will become apparent upon reference to the discussionbelow and to the drawings which are given for illustrative purposes.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a schematic perspective view depicting a preferred embodimentof the apparatus employed for carrying out the invention;

FIG. 2 is a fragmentary front elevation view of an apparatus as depictedin FIG. 1, showing an aspirator in section and a two-planar deflectorattached to the exit end of the aspirating means;

FIG. 3 is a fragmentary side elevation of the apparatus as depicted inFIG. 2 showing parts of the aspirator removed and turned 90 degreesclockwise from the position of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings andparticularly to FIG. 1, a bundle of freshly formed filaments .12 enterinlet aperture 57 of an aspirator such as aspirating jet 14. Thefilaments are formed from the spinnerette of a melt spinning apparatus(not shown). Subsequent to spinning, the filaments may also beattenuated and oriented on a drawing apparatus (also not shown).Filament bundles having a broad range of denier, i.e. 30' to 3400 totaldenier, may be used in the apparatus of this invention. Within theaspirating jet 14, the filaments are acted upon by a high velocity fluidmedium such as air, which is supplied through inlet conduit 13.Aspirating jet 14 comprises an air nozzle 9',

4 a collar 10 and a diffuser 11. The filament bundle 12 is forwarded viathe high-velocity aspirating medium from the jet exit 17 to thetwo-planar deflector 22 wherein at least a majority of filaments ofbundle 12 are deflected from such two-planar deflector 22 onto receivingsurface 20. Air stream deflection and its attendant turbulence spreadsand opens the filament bundle 12 deflecting from two-planar deflector 22in a wide and random manner, as

shown in FIG. 1. The two-planar deflector 22. is clamped substantiallyrigidly near the exit end of jet 14 via any suitable means, such asextension 16 and clamp 15 at the exit end of aspirating jet .14. Onreceiving surface 20, preferably a foraminous continuously movingconveyor, with a suction chamberll provided beneath that portion ofconveyor 20 on which the filaments are being laid down, the filamentsare deposited in a random manner to form web 23.

In FIG. 2, the aspirating jet comprises: a hollow air nozzle 9 which isexternally threaded at each end and which has an air inlet conduit 13attached to its upper end; a hollow collar 10 which is internallythreaded at both ends so as to connect air nozzle 9 with diffuser 11 andwhich has an inlet aperture 57 for receiving filament bundle 12; and ahollow diffuser 11 which is externally threaded at its upper end andthrough which the filaments and high velocity air are propelled ontotwo-planar deflector 22 and thereafter onto a receiving surface. The

annular internal aperture 57 is arranged to direct the filamentsentering therein downwards, i.e. in direction of air flow. The internaldimensions of collar 10 and of diffuser 11 are arranged so as tominimize twisting, knotting and entanglement of the filaments passingtherein. By Way of example only, the diameter of nozzle passageway 51 ismost preferably from 20 percent to 33 percent of the nozzle passagewaylength. Also, crosssectional area of nozzle passageway 51 is preferablyfrom 25 percent to 35 percent of the cross-sectional area of diffuserpassageway 54. Further, the diameter of diffuser passageway 54 ispreferably from 2 percent to 10 percent of the length thereof. Stillfurther, the maximum diameter of diffuser entrance chamber 53, which isconical in shape, is most preferably approximately two times thediameter of the diffuser passageway 54. The crosssectional area ofdiffuser passageway 54 is designed such that the cross-sectional area offilament bundle 12 passage therein ranges from 0.1 percent to 5 percent,preferably from 0.2 percent to 1.5 percent, of the diffuser passagewaycross-sectional area. The respective lengths and diameters of air nozzleentrance chamber 50 and of collar chamber 52 are not critical. However,such lengths and diameters should be used as are practical; i.e.compatible with the overall operation of the present process.

The first plane 18 and the second plane 19 of the two-planar deflector22 are each of a width W which is suflicient to deflect at least amajority of the filaments emanating from the aspirator exist passageway17. It is not essential that any width of plane 18 equal any width ofplane 19. The widths W of each plane may be varied to suit theparticular situation. Each situation is dependent on such variables asair velocity at the jet exit, jet-deflector distances, type andproperties of polymer from which the filaments are made, and desiredfilament laydown pattern. Preferably, a width of the first plane 18ranges from approximately 5 to 15 times, and more preferably from 7 to13 times, the diameter of the aspirator exit passageway 17 and a widthof the second plane 19 ranges at least 5 times, more preferably from 7to 20 times, the diameter of exit passageway 17. These enumerated rangesfor plane 18 width and plane 19 width are not limiting and are given inorder to provide suitable widths for deflecting at least a majority ofthe filaments exiting from jet 14. In an alternative preferredembodiment, the second plane width which is farthest from the jet exit17 may be substantially wider than the other width of second plane 19,so as to increase the capacity of the twoplanar deflector in deflectinga greater number of filaments when this is desired.

Although the two-planar deflector 22 works especially compatibly withthe preferred aspirating jet 14 as described in FIG. 2 and as describedin greater detail in patent application Ser. No. 184,542 entitledProcess and Apparatus for Production of a Nonwoven Web, filed on Sept.28, 1971 in the name of Walter P. Lipscomb and Garland L. Turner, it hasbeen designed to work compatibly with many conventional aspirators. Ingeneral, such conventional aspirators are especially suitable for usewith the apparatus of this invention if these aspirators forward thefilaments at high velocity, generate sufficient pull therein to maintainthe filaments under minimum tension, open and separate the filamentbundle during the exiting of the filaments from the aspirators, andprevent filaments from undergoing any substantial twisting, knotting, orentanglement therein.

Referring now to FIG. 3, the critical angular and dimensionalrelationship of the components of the twoplanar deflector to theaspirator jet exit is shown. The first plane 18 is aflixed rigidly tothe exit of aspirating jet 14 by clamp 15 via a suitable extension 16,which is compatible operatively with plane 18. Plane 18 and plane 19 ofthe two-planar deflector, extension 16 and clamp 15 are designed toremain substantially rigid during normal operation of the apparatus.Planes 18 and 19 are positioned near the exit of the aspirator 14 suchthat a majority of said filaments impinge on the two-planar deflectorafter exiting from the aspirator. Plane 18 or its projection intersectsplane 19, forming an angle greater than 90 degrees between the impingingsurface of plane 18 and the impinging surface of plane 19 in order tomaintain control over the extent of filament deflection from thetwoplanar deflector. Plane 18 and plane 19 are constructed of a suitablematerial which is substantially rigid and does not degrade the filamentswhich contact it; e.g. shim brass or stainless steel. The angles whichthe two planes make with a line parallel to the center line of theaspirator are critical to the operability of this invention. Forconvenience, on is defined as the acute angle which the length of plane18 makes with a line which is parallel to the center line of the exitpassageway 17 of aspirating jet 14, and is defined as the acute anglewhich a straight-line extension of first plane 18 makes with the secondplane 19. We have found that a judicious choice of a and (3 assures ahigh degree of filament dispersal and separation. An exact determinationof a and B is dependent on such variables as the type of polymer fromwhich the filaments are made, the physical properties of the filamentswhich contact the two-planar deflector, the speed of filaments at thepoint of contact with the two-planar deflecto the desired properties ofthe resultant nonwoven web of filaments, and the desired filamentlaydown pattern. In order to obtain a suitable degree of filamentspreading, a should range between 0 degree and 60 degrees, preferablybetween 25 degrees and 50 degrees. Similarly, [3 should range between 20degrees and 85 degrees, preferably between 35 degrees and 60 degrees.The sum of a and B is less than 90 degrees and ranges preferably between20 degrees and 89 degrees, more preferably between 45 degrees and 87degrees. Use of the preferred values for a and 6 under the conditions ofthis invention, in comparison to a similar apparatus without thetwo-planar deflector, assures a surprisingly greater spreading of thefilaments prior to deposition on the receiving surface and asurprisingly greater random distribution of uniformly distributedfilaments within a wider web formed on the receiving surface. Experiencehas shown that a distance of approximately 3.5 to 26 times, morepreferably from 4 to 15 times, the diameter of aspirator passageway exit17 between the exit end of jet 14 and the area of initial substantialcontact on the surface of two-planar deflector 22 has yieldedsatisfactory results. With values of such aspirator-deflector contactdistance less than 3.5 times the jet exit diameter, filament depositionprofiles are characterized by a detrimentally high degree of filamentcompacting and agglomeration. On the other hand, with values greaterthan 26 times the exit diameter, such profiles are characterized byinadequate dispersing as a result of reduced air velocities at suchgreater distances.

The length L1 of first plane 18 and the length L2 of second plane 19 aredesigned to be of a total dimension which is suificient to deflect atleast a majority of the filaments exiting from the aspirator passageway54. For similar reasons as discussed above for plane widths, the lengthsof each plane may be varied to suit the particular situation. Toaccomplish a suitable degree of deflection when the two-planar deflectorhas quadrilateral planes, L1 as measured in a direction proceeding fromthe aspirator exit ranges preferably approximately from 3.5 to 20 times,even more preferably from 4 to 10 times, the diameter of the aspiratorexit passageway 54. Also L2 ranges preferably approximately from 1.5 to25 times, more preferably from 2 to 4 times, the diameter of passageway54. With values of L1 less than 3.5 times and L2 less than 1.5 times thediameter of passageway 54, no significant improvement in filamentspreading was found when compared against apparatus using the jetWithout the twoplanar deflector. With values of L1 greater than 20 timesand L2 greater than 25 times the diameter of passageway 54, the filamentdeposition profile was characterized by a relatively highly nonuniformdistribution of filaments due to excessive randomness as a result ofloss of control of filament laydown pattern.

The two-planar deflector is most preferably placed near the aspiratorexit in a manner such that the widths of each plane are substantiallyperpendicular to the direction of forward motion of the moving receivingsurface. Such placement assures symmetrical and uniform dispersal of thefilaments on the receiving surface. Alternatively, the two-planardeflector may be placed such that the widths are at an angle whichdeviates from a direction perpendicular to the direction of motion ofthe receiving surface. However, such non-perpendicular placement is madeat a sacrifice of uniform distribution of filaments across the laydownarea during deposition; in some cases, depending on the intended usage,of the nonwoven web product, this may be desirable.

We recognize that the planes of the two-planar deflector of thisinvention are not limited to quadrilateral forms. Planes of a greaternumber of sides than four may be used. However, as the number of sidesis increased, ex-

penses in production of the plane may increase without any substantialimprovement in the degree of spreading occurring.

In operation, the aspirating medium, which may be a pressurized fluidsuch as air, is introduced from a supply source, not shown, into chamber50, at a pressure preferably ranging from 30 to p.s.i.g. Such mediaenters and flows through nozzle passageway 51 and exits therefrom as ahigh velocity stream. The pressurized state of the aspirating media iscontingent upon several conditions and thus may be varied to meet thespecified circumstances. Some factors which influence operatingpressures are the aspirating jet design, aspirating media, pressureconsumed, type and nature of filament-forming polymer, degree oforientation to which filaments have been subjected, and the resultingproperties of the nonwoven product. The high velocity fluid streamexiting nozzle passageway 51 engages filaments 12 entering the aperture57 with sufficient energy to propel the filaments through collar chamber52 into the diffuser 11, which is characterized by an initiallydiverging chamber 53. Subsequently, the propelled filaments aredispersed from diffuser passageway exit 17 in a wide and random mannervia deflection from the two-planar deflector 22. Then the filaments aredeposited on a receiving surface which normally takes the form of aconveyor belt moving at a predetermined constant speed and at apredetermined distance from the exposed width of the second plane 19 ofthe two-planar deflector 22. The receiving surface should be placedbelow the two'planar deflector of this invention at a distance such thateffectiveness and efficiency of random dispersal of filaments thereon ina uniform manner is achieved.

The following example is provided as further illustra-v tive of thepresent invention. The enumeration of details therein, however, shouldnot be considered as restrictive of the scope of this invention.

In an example, nylon 6 is melt spun into a 32-filament bundle 12 of 150'denier. The filament bundle 12 is subsequently introduced intoaspirating jet 14 via aperture 57. In collar chamber 52, the filamentsare subjected to air as the aspirating medium at a pressure of 30p.s.i.g. The filaments 12 are forwarded to and through diffuserpassageway 54 by the aspirating jet stream. Thereafter, the filaments 12exit from jet 14 onto a two-planar deflector 22. The two-planardeflector 22 has a /z-inch long, %-inch wide first plane 18, and fivinchlong, inch wide second plane 19, an angle a of 40 degrees and an angle[3 of 45 degrees. The filaments exhibit an initial point of substantialcontact on two-planar deflector 22 at a distance from jet exitpassageway 54 of approximately inch. Upon deflection from two-planardeflector 22, filaments 12 open up considerably and are deposited oncontinuously moving, foraminous, horizontal conveyor 20 which is movingat a speed of 8 feet per minute and is at a distance of 8 inches fromthe closest portion of the two-planar defiector 22. The nonwoven webproduced is characterized by having a random filament distributionthroughout. The appearance of the web is uniform and is essentially freeof filament aggregates.

The nonwoven web or other useful construction processed from a coherentfilament bundle which is prepared in accordance with this invention mayserve a variety of useful purposes, particularly in the manufacture ofnonwoven fabrics, such as carpet backing, wall covering, insulation,coating substrates, interfacing, filters, and the like.

Various modifications and other advantages will be apparent to oneskilled in the art, and it is not intended that this invention belimited to details presented by way of illustration except as requiredby express limitations in the appended claims.

What is claimed is:

1. In an apparatus for depositing filaments onto a moving receivingsurface in a randomly dispersed manner to form a nonwoven web ofrandomly disposed filaments substantially uniformly distributedthroughout said web, said apparatus comprising an aspirating means forforwarding said filaments at high velocity to said moving receivingsurface, the improvement comprising a two-planar deflector splayingmeans for augmenting spreading of, while advancing said filaments fromsaid aspirating means to said moving receiving surface, said two-planardeflector consisting of a first plane rigidly aifixed in one spatialposition and a second plane being rigidly afiixed in another spatialposition, said two-plane deflector being positioned near the exist ofsaid aspirating means such that a majority of said filaments exitingfrom said aspirating means impinge on said two-planar deflector and suchthat said first plane or its straight-line extension intersects saidsecond plane in a manner so as to form an angle greater than 90 degreesbetween the impinging surfaces of said planes, said first planeproducing an acute angle a of approximately bet-ween 0 degree and 60degrees with a line parallel to the center-line of the exit passagewayof said aspirating means, a being measured in the general direction offorward motion of said moving receiving surface, and said second planeproducing an acute angle 5 of approximately between 20 degrees anddegrees with the extension of said first plane in said direction, thesum of said angle at and said angle 5 being less than degrees.

2. The apparatus of claim 1 wherein a is between 25 degrees and 50degrees, 18 is between 35 degrees and 60 degrees, and the sum of a and 5is between 45 degrees and 87 degrees.

3. The apparatus of claim 2 wherein said two-planar deflector is affixedin a manner such that there is a distance ranging approximately from 3to 26 times the diameter of said aspirating means exit passagewaybetween said aspirator exit means and the area of initial substantialcontact of said filaments on said two-planar deflector.

4. The apparatus of claim 3 wherein said distance ranges from 4 to 15times said aspirating means exit passageway diameter.

5. The apparatus of claim 3 wherein said two-planar deflector hassubstantially rectangular planes, said first plane having a length in adirection proceeding from said aspirating means exit ranging from 3.5 to20 times said aspirating means exit passageway diameter and a widthranging from 5 to 15 times said exit passageway diameter, and saidsecond plane having a length in a direction proceeding from saidaspirating means exit ranging from 1.5 to 25 times said exit passagewaydiameter and a width of at least 5 times said passageway diameter.

6. The apparatus of claim 5 wherein said first plane length ranges from4 to 10 times said aspirating means exit passageway diameter, said firstplane width ranges from 7 to 13 times said exit passageway diameter,said second plane length ranges from 2 to 4 times said exit passagewaydiameter, and said second plane width ranges from 7 to 20 times saidexit passageway diameter.

7. The apparatus of claim 5 wherein 0c is 40 degrees and B is 45degrees.

References .Cited UNITED STATES PATENTS 3,692,618 9/1972 Dorschner etal. 156-181 3,655,862 4/1972 Dorschner et al. 264290 3,341,394 9/1967Kinney 156167 3,423,266 1/1969 Davies et al. l56-167 2,736,676 2/1956Frickert, Jr. 156441 DANIEL J. FRITSCH, Primary Examiner US. Cl. x.R.

